pub fn odd_fibnacci_sum(threshold: u32) -> u32 {
    let mut a = 0;
    let mut b = 1;
    let mut c;
    let mut result = 0;
    while a < threshold {
        if (a & 1) == 1 {
            result += a;
        }
        c = a + b;
        a = b;
        b = c;
    }
    return result;
}
